Disk drives are a type of information storage device that store information on at least one spinning disk. Other types of information storage devices include, for example, magnetic tape drives which retrieve stored information on magnetic tape (e.g. linear tape drive, helical scan tape drive). There are several types of disk drives. For example, there are so-called floppy disk drives, which store information on removable magnetic disks. There are also optical disk drives, which typically retrieve information stored on removable optical disk media. Magnetic hard disk drives typically store information on non-removable rigid magnetic disks. Also for example, there are magneto-optical disk drives, which share some of the characteristics of optical disk drives and magnetic hard disk drives.
The contemporary magnetic hard disk drive 100 that is shown in FIG. 1 includes a disk drive base 102 and at least one annular magnetic disk 104. Each disk 104 is rotated by a spindle 106 that is attached to the disk drive base 102. Each disk 104 includes a plurality of magnetic tracks for storing data, disposed upon opposing major surfaces of the disk 104. The data of the plurality of magnetic tracks is written and read by a head 122 that is attached to and is part of head gimbal assembly (HGA) 124. HGA 124 is attached, typically by swaging, to an arm 114 of rotary actuator 110. Rotary actuator 110 is rotably attached to the disk drive base 102 via a pivot bearing cartridge 118. During operation, the rotary actuator 110 is rotated by action of voice coil motor (VCM) 112 to position the head(s) at desired data tracks on the surfaces of the disk(s) 104. When the disk drive is not in operation, the heads are retracted from the disk surface by a head loading ramp 120.
The disk drive base 102 includes an arcuate shroud wall that is disposed closely around a portion of the outer periphery of the disk 104. Such a base feature may somewhat reduce or attenuate disk flutter and other dynamic vibrations. However, the beneficial effect of such shrouding may be diminished because the shroud must have a large opening or gap (at the left side of disk 104 in the view of FIG. 1) to allow access and movement by the arm(s) 114 of the actuator 110, between and over the disk surfaces. Therefore, the arcuate shroud cannot completely encircle the disk 104, but rather spans an arc that is much less than 360 degrees. Contemporary disk drives also typically include other openings or gaps in the shroud. For example, the disk drive base 102 of FIG. 1 includes an additional shroud gap to accommodate recirculation filter 108, and another shroud gap to direct air flow induced by the rotation of the disk(s) 104 to the recirculation filter 108.
Therefore, there is a need in the art for a practical disk drive design that can enhance the performance of a stationary shroud in attenuating disk flutter and other dynamic vibrations.